Method and apparatus for replication of angular position of a humeral head of a shoulder prosthesis

ABSTRACT

A jig for trialing a head and conjoining portion of a humeral (shoulder) prosthesis and transferring the spatial positioning to a final implant allows a surgeon to adjust humeral head position thereof in three-dimensional space with respect to a humeral component of the humeral prosthesis that has been either previously implanted into a humerus of a patient or not. The jig utilizes a rotatable body such as a sphere that is non-translatable relative to a jig body. A trial implant construct, having a head and neck that is fixed relative to one another (is spatially positioned), is placed in the jig with the neck thereof in contact with the rotatable sphere. As the head is caused to align with markings on the jig and situated flush with the jig, the rotatable sphere replicates the angular position of the neck with respect to a fixed position head. A final implant construct whose components are not fixed relative to one another, is placed in the jig which automatically transfers the spatial positioning of the trial implant construct to the final implant construct.

CROSS-REFERENCE TO RELATED APPLICATIONS

Cross-reference is made to co-pending U.S. Patent Application filed oneven date herewith entitled “Shoulder Prosthesis Having a RemovableConjoining Component Coupling a Humeral Component and Humeral Head andProviding Infinitely Adjustable Positioning of an Articular Surface ofthe Humeral Head” by co-inventors Robert J. Ball and Jeffrey M. Ondrla,and commonly assigned.

BACKGROUND

1. Field of the Invention

The present invention relates to prosthetic devices particularlyshoulder prostheses and, more particularly, to a method and apparatusfor replication of angular position of a humeral head of a shoulderprosthesis.

2. Background Information

The state of the prosthetic shoulder market has progressed such that asurgeon generally approaches shoulder replacement surgery in one of twostrategic ways. One strategic manner is to perform the shoulderreplacement surgery in accordance with a manufacturer's shoulderprosthesis or shoulder prosthesis product line. Particularly, a surgeonis provided with instrumentation and technique guidelines for theparticular shoulder prosthesis or prosthesis line. The guidelines and/orinstrumentation direct or dictate the angle of humeral head resectionfor the implant (prosthesis). This angle is in relation to the humeralintramedullary (IM) canal and is designed to match an optimum set ofangles already present in the prosthetic design.

Another strategic manner is to perform the shoulder replacement surgeryin accordance with a patient's anatomy. Particularly, the humeral headis resected according to angles perceived to be “anatomic” in theopinion of the surgeon, not according to angles already present in theprosthetic design. The prosthesis is designed such that theconfiguration of the prosthesis is intraoperatively adjustable. Thisallows the prosthesis to be adjustable whereby it can match the boneypreparation.

Even with respect to these two divergent manners of surgical strategy, acommon problem in shoulder surgery is matching the humeral resectionangle to the predetermined angle designed into the prosthesis. Thisangle may described the angle between a prosthetic collar and thediaphyseal section of the stem. In the case of a collarless stem, theangle may describe the difference between the long axis of the stem andthe inferior surface of the prosthetic head. It is considered optimalfor fixation and biomechanics if the resected angle and the angle of theprosthesis are identical—thereby allowing intimate contact between thesuperior surface of resected bone and the inferior surface of theimplant.

Moreover, the angular version in which the prosthesis is implanted willhave a significant impact on the biomechanics of the prosthetic joint.Currently, most shoulder prosthesis systems on the market dictate thevarus/valgus angle of the bone cut. This strategy does not allow thesurgeon to easily alter biomechanics after the prosthesis has beentrialed, much less implanted.

There are two known products currently marketed that attempt to resolveat least one of the above-noted issues. First, the Tornier-Aequalissystem provides a modular junction within the metaphyseal region of thestem which allows a small block between the stem and humeral head to beinterchanged. This block is available in multiple angles, thus allowingthe surgeon to select the block that best fits the boney anatomy asresected. This system, however, has two primary weaknesses. First, theuse of modular blocks obviously forces the design to only allow angularadjustments in finite increments. Second, the need to adjust the anglethrough modular blocks forces the surgeon to remove the stem, change outa component, and reset the stem. This presents inconvenience, as well asrisk for interfering with resected bone and compromising fixation.

A second product currently marketed as a solution to the problemsaddressed above is the CenterPulse Anatomica. This product provides ahumeral head that is infinitely adjustable in varus/valgus andanterior/posterior angles relative to the stem portion of theprosthesis. This is accomplished through a spherical shaped protrusionon the superior surface of the stem that fits into a spherical recess inthe humeral head. These mating surfaces allows the head to bearticulated about the stem, thus allowing adjustable positioning of thehead. The head can be locked in a position relative to the stem. Thissolution provides adjustment of the neck-shaft angle as well as beingable to affect adjustment of the version through flexibility in theanterior/posterior angle. The locking means, however, is sub-optimal.Particularly, the locking mechanism, requires the turning of a lockingscrew that has its head facing lateral and inferior, for which there isno access once the stem has been cemented. This eliminates the abilityto adjust head position on the fly, and forces a total revision ifarticular surfaces ever need to be revised. Lastly, the protrusion onthe humeral stem even when the humeral head is not in place limits thesurgeon's access to the glenoid in preparation for a glenoidreplacement.

It should be appreciated that it is desired to have a prosthesis that isintraoperatively adjustable so that it can match the boney preparation.One such prosthesis that has attempted to provide this design feature ismade by Sulzer Anatomica. A problem with the Sulzer Anatomica device,however, is replication of the head angular position between the trialprosthesis and the final implant is difficult. In order to alleviatethis problem, Sulzer Anatomica provides a jig. The Sulzer Anatomic jig,however, is complicated and cumbersome to use.

Particularly, the Sulzer Anatomica jig has two problems. One problem isthat the head position is taken directly from the long axis of thehumeral stem. Thus, the trail and implant stems are required to adjustand replicate this position. This means that the Sulzer Anatomica has alarge number of components to handle, and the position cannot beadjusted with the stem in vivo. Another problem is that the jig is aquite complicated table-top device. This requires transferring theimplant to the back table and setting the implant (stem and head) intothe jig. This is technically challenging and time consuming.

With a shoulder prosthesis that allows a surgeon to adjust the angularposition of the humeral head (i.e. adjust the articular surface of thehumeral head relative to the humeral stem/component and/or bone, amethod must be available for trialing the prosthesis. When the trialprosthesis is implanted, several adjustments can be made to set theangular position of the prosthetic head relative to the humeral stem. Ameans must be available for transferring the settings obtained duringthe trialing process to the final implant.

What is thus needed in view of the above is a better method for trialinga shoulder prosthesis.

What is further needed in view of the above, is a trialing jig thatallows the transfer of settings obtained during the trialing process tothe final implant.

What is yet further needed in view of the above, is a quick and easytrialing jig that allows the transfer of setting obtained during thetrialing process to the final implant.

SUMMARY

A jig and method of use for trialing a head and conjoining portion of ahumeral (shoulder) prosthesis and transferring the spatial positioningto a final implant allows a surgeon to adjust humeral head positionthereof in three-dimensional space with respect to a humeral componentof the humeral prosthesis that has been either previously implanted intoa humerus of a patient or not. The jig utilizes a rotatable body such asa sphere that is non-translatable relative to a jig body. A trialimplant construct, having a head and neck that is fixed relative to oneanother (is spatially positioned), is placed in the jig with the neckthereof in contact with the rotatable sphere. As the head is caused toalign with markings on the jig and situated flush with the jig, therotatable sphere replicates the angular position of the neck withrespect to a fixed position head. A final implant construct whosecomponents are not fixed relative to one another, is placed in the jigwhich automatically transfers the spatial positioning of the trialimplant construct to the final implant construct.

According to one embodiment, the jig includes a flat plate in which ispositioned a rotatable sphere. The sphere fits into the plate such thatthe sphere can be rotated about at least two axes that are perpendicularand extend through the center of the sphere, but which cannot translaterelative to the plate. A locking means is provided to releasably lock orfix the angular position of the sphere relative to the plate by means ofa set screw. The sphere has a hole extending therethrough that receivesa neck or extension of a humeral head of the implant construct. Theextension from the head is presented into the hole of the sphere. Thesphere rotates such that the flat side of the head can rest flat uponthe flat plate. The sphere is releasably locked in place and the trialimplant construct is removed. A final implant construct is placed in thelocked sphere. The head is rotated such that the flat side thereof restsupon the flat plate. Thereafter, the head and neck are locked inposition. In this manner, the final implant construct is oriented in thesame spatial position as the trial implant construct.

In one form, the subject invention provides a jig for transferringspatial positioning of a humeral head of a first construct relative to aconjoining member of the first construct to a second construct having ahumeral head and conjoining member. The jig includes a body defining aflat surface, a cavity within the body, a pivoting member disposedwithin the cavity, the pivoting member having a configured boreaccessible through the body and adapted to freely pivot within thecavity, and locking means situated in the body and adapted toselectively engage the pivoting member to releasably fix a rotationalposition of the pivoting member. The configured bore is adapted toreceive a conjoining member of the first construct and orient theconjoining member relative to a position of the head on the flat surfaceof the body via pivoting of the pivoting member, the locking meansreleasably fixing rotational position of the pivoting member duringwhich the first construct is removed and a conjoining member of a secondconstruct is placed therein for alignment according to the fixedrotational position of the pivoting member as a head of the secondconstruct is placed on the position of the head of the first constructon the body, the conjoining member then affixed to the head of thesecond construct.

In another form, the subject invention provides a jig for transferringspatial orientation of a humeral head to a conjoining member of a firstconstruct to a humeral head and conjoining member of a second construct.The jig includes a body having an upper surface, a spherical cavity, andan opening in the upper surface. A sphere is disposed in the sphericalcavity and has a bore configured to receive a neck of a first construct,the sphere being adapted to freely rotate within the spherical cavityand without translation relative to the body. Locking means is situatedin the body and is adapted to selectively engage the sphere toreleasably fix a rotational position of the sphere. The configured boreis adapted to receive a neck of the first construct and orient the neckrelative to a position of the head on the flat surface of the body viarotation of the sphere, the locking means releasably fixing rotationalposition of the sphere during which the first construct is removed and aneck of a second construct is placed therein for alignment according tothe fixed rotational position of the sphere as a head of the secondconstruct is placed on the position of the head of the first constructon the body, the neck then affixed to the head of the second implantconstruct.

In yet another form, the subject invention provides a method oftransferring spatial orientation of a first construct having a humeralhead adapted to be releasably affixed to a conjoining member to a secondconstruct having a humeral head adapted to be releasably affixed to aconjoining member. The method includes the steps of: (a) fixing aspatial orientation of a humeral head relative to a conjoining member ofa first construct; (b) placing the conjoining member of the firstconstruct into a jig, the jig comprising: a body defining a flatsurface; a cavity within the body; a pivoting member disposed within thecavity, the pivoting member having a configured bore and adapted tofreely rotate within said cavity; and locking means situated in the bodyand adapted to selectively engage the pivoting member to releasably fixa rotational position of the pivoting member; wherein the configuredbore is adapted to receive a conjoining member of the first constructand orient the conjoining member relative to a position of the head onthe flat surface of the body via rotation of the pivoting member; (c)fixing the rotational position of the pivoting member the locking means;(d) removing the first construct; and (e) placing a conjoining member ofa second construct in the jig for alignment according to the fixedrotational position of the pivoting member as a head of the secondconstruct is placed on the position of the head of the first constructon the body, the conjoining member then affixed to the head of thesecond construct.

The subject invention is advantageous over existing technology in that(1) the subject invention is cost effective, i.e. the subject deviceand/or method of use is simple in design and construction, thus reducingcosts of manufacture, (2) the subject device and/or method of use iseasy to use, i.e. the subject device and/or method of use essentiallycompletes the task of trialing in three steps with no requirements formeasuring angles or remembering measurements, (3) the subject inventionis very compact and thus can perform trialing in an area proximate thesurgical incision as opposed to transferring from/to a back table, and(4) the subject device and/or method of use is reliable, i.e. there arefew moving parts to fail or loose. All of the above provides a simple,reliable, and easy to manufacture trialing system, i.e. device and/ormethod of use thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is an exploded perspective view of an exemplary shoulderprosthesis incorporating the features of the subject invention inaccordance with the principles thereof;

FIG. 2 is a plan and partial sectional view of the humeral component ofthe exemplary shoulder prosthesis of FIG. 1;

FIG. 3 is an enlarged front plan view of the neck body of the conjoiningmember of the exemplary shoulder prosthesis of FIG. 1;

FIG. 4 is an enlarged rear plan view of the neck body of the conjoiningmember of the exemplary shoulder prosthesis of FIG. 3;

FIG. 5 is an enlarged front plan view of the neck body of FIG. 3 showingthe internal structure thereof;

FIG. 6 is an enlarged plan view of the adjustment/locking member of theconjoining member of the exemplary shoulder prosthesis of FIG. 1;

FIG. 7 is an enlarged perspective view of the adjustment/locking memberof FIG. 6;

FIG. 8 is an enlarged perspective view of the head of the shoulderprosthesis of FIG. 1;

FIG. 9 is another enlarged perspective view of the head of FIG. 8 froman underside perspective;

FIG. 10 is a sectional view of the head of FIG. 8 taken along line 10—10thereof;

FIG. 11 is a sectional view of the head of FIG. 8 taken along line 11—11thereof;

FIG. 12 is a front plan view of interaction between the head and neckillustrating a manner of conjoining in accordance with the principles ofthe subject invention.

FIG. 13 is a front plan view of interaction further to the interactionof FIG. 12 between the head and neck illustrating the manner ofconjoining in accordance with the principles of the subject invention.

FIG. 14 is a side sectional view of the exemplary humeral head andconjoining member with the humeral head in one particular orientation;

FIG. 15 is a side sectional view of the exemplary humeral head andconjoining member with the head in another particular orientationillustrating in conjunction with FIG. 14 the manner of spatialorientation of the head relative to the conjoining member and/or thehumeral component;

FIG. 16 is a side sectional view of the exemplary humeral head andconjoining member with the head in another particular orientationillustrating in conjunction with FIGS. 14 and 15 the manner of spatialorientation of the head relative to the conjoining member and/or thehumeral component;

FIG. 17 is a side sectional view of the exemplary humeral head andconjoining component with the head fixed a particular orientationillustrating the manner of fixation with the locking member insertedinto the neck;

FIG. 18 is a side view of an exemplary shoulder prosthesis with aportion thereof in sectional particularly depicting the manner ofassembly thereof;

FIG. 19 is an enlarged side sectional view of an exemplary alternativeembodiment of a humeral head;

FIG. 20 is perspective view of a trialing jig for a shoulder prosthesis;

FIG. 21 is a sectional view of the trialing jig for a shoulderprosthesis of FIG. 20 taken along line 21—21 thereof;

FIG. 22 is a sectional view of the trialing jig of FIG. 20 in likemanner to FIG. 21, particularly depicting a conjoining component beingtrialed on a humeral head in accordance with the principles of thesubject invention; and

FIG. 23 is an exploded sectional view of a further exemplary alternativeembodiment of a shoulder prosthesis in accordance with the principles ofthe subject invention.

Corresponding reference characters indicate corresponding partsthroughout the several views. Like reference characters tend to indicatelike parts throughout the several views.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and will herein by described in detail. Itshould be understood, however, that there is no intent to limit theinvention to the particular forms disclosed, but on the contrary, theintention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the invention.

Referring now to FIG. 1 there is shown an exemplary embodiment of ashoulder prosthesis, generally designated 20. The shoulder prosthesis 20includes a humeral component or stem 22, a conjoining and/or adjustmentmember or means 24, and a head 26. The head 26 is adapted, configuredand/or operative to be received on the conjoining member 24 or viceversa (i.e. the conjoining member 24 is adapted, configured and/oroperative to be received on the head 26) depending on the configurationsof the head 26 and the conjoining member 28 and/or one's perspective.Thus, while the remaining text describes the conjoining of the head andthe conjoining member, it should be appreciated that both contexts arecovered thereby.

Particularly, the head 26 is adapted, configured and/or operative to bereleasably affixed to the conjoining member 24. More particularly, thehead 26 is adapted, configured and/or operative to be releasably lockedto the conjoining member 24 in a particular or selectable rotationaland/or angular orientation relative to the conjoining member 24 and/orthe humeral component 22 as described further below. The conjoiningmember 24 is adapted, configured and/or operative to be received on thehumeral component 22. Particularly, the conjoining member 24 is adapted,configured and/or operative to be releasably received on the humeralcomponent 22. All of the components of the shoulder prosthesis 20 aremanufactured from a material or materials such as are known in the artfor such implants.

As depicted in FIG. 1, the conjoining member 24 includes a neck, neckmember or the like 28 and a locking and/or adjustment member, screw orthe like 30. The locking member 30 cooperates with the neck 28 toreleasably lock or fix the head 26 in a particular orientation on theneck 28. When the conjoining member 24 is releasably disposed on thehumeral component 22, the head 26 is also releasably locked or fixedwith respect to the humeral component 22. As explained more fully below,the conjoining member 24 is also releasably locked or affixed to thehead 26 such that the head 26 and/or the conjoining member 24 are lockedagainst axial movement between the two.

Referring now to FIG. 2, the humeral component 22 is depicted. Thehumeral component 22 is characterized by a body 32 having a stem or stemportion 34 and a neck or neck portion 36. The humeral component 22 mayor may not have fins, collars, suture holes or the like. Therefore, suchare not shown in FIG. 2. The neck 36 has a preferably substantially flator planar surface 38 having a connector, connection or connectionreceptacle 40 extending therefrom into the neck 36. In one form, theconnection receptacle 40 is defined by an inner wall 42. The connectionreceptacle 40 may be a concavity, recess, or the like. Preferably, andas shown, the connection receptacle 40 has a tapered inner wall 42. Morepreferably, the inner wall 42 defines a frusto-conical shaped concavity.Preferably, but not necessarily, an axis of the connection receptacle 40is substantially perpendicular to the surface 38. The connectionreceptacle 40, however, may be a protuberance, boss, flange or the like(i.e. a convexity) rather than a concavity. In both cases, a matingelement would be opposite (complementary) in configuration.

The humeral component 22 is adapted, configured and/or operative suchthat the stem 34 thereof is insertable into a humeral canal of a humerus(not shown) of a patient (not shown) after appropriate resection of thehumerus. Particularly, the humeral component 22 is inserted into thehumerus of the patient such that the head 36 is within the humerus andthe surface 38 is substantially co-planar with a resection surface ofthe humerus such as is known in the art. This allows access to theconnection receptacle 40 after implantation of the humeral component 22into a humerus.

Referring now to FIGS. 3 and 4, the neck 28 of the conjoining member 24is depicted. The neck 28 is characterized by a body 46 defining a firstend 48 and a second end 50. In keeping with the configuration of theconnection receptacle 40 as depicted in the Figures, the first end 48 isformed as a configured convexity or protuberance. In all cases, thefirst end 48 is configured in a complementary manner to the connectionreceptacle 40 of the humeral component 22, in whatever form theconnection receptacle 40 may take. In the embodiment shown, the firstend 48 is formed as a tapered cylinder or of a frusto-conical design.

The second end 50 is formed with a connector that may be a configuredconvexity or concavity. In the Figures, the second end 50 is formed as asphere, spheroid or the like. The spheroid 50 is preferably a truesphere but may deviate therefrom and is solid except for the structuresdescribed herein. The spheroid 50 is shown with a first flat or flatportion 52 on a side thereof and a second flat or flat portion 54 thatis disposed on another side thereof that is preferably, but notnecessarily, diametrically opposite the first flat 52. The flats 52 and54 preferably, but not necessarily, have the same configuration. Theflats 52 and 54 form planes that are preferably, but not necessarilyparallel. The planes of the flats 52 and 54 are also preferably, but notnecessarily, parallel with an axial plane of the conjoining body 46. Theflats 52 and 54 are disposed on the spheroid 50 such that planes definedthereby are not perpendicular to the axis of the first end 48.

While two flats are shown, it should be appreciated that the spheroid 50may have only one flat or the spheroid 50 may have more than two flats.Furthermore, the spheroid 50 may have a key, keys, a keying structure orkeying structures other than flats thereon depending on theconfiguration of a complementary connector, receptacle or the like ofthe head 26.

In a further form, the shoulder prosthesis may not have flats or anysuch corresponding structure. In this form, the humeral head is receivedonto the conjoining member 24 and fixed in angular position as describedherein. Thus, it is not necessary to have flats or any suchcorresponding structure.

The spheroid 50 also has a first radial slit 56 (see FIG. 3) and asecond radial slit 60 (see FIG. 4) that together define a continuousfirst radial slot. The spheroid 50 may further has a third radial slit58 (see FIG. 3) and a fourth radial slit 62 (see FIG. 4) that togetherdefine a continuous second radial slot. In one form that is not shown,the spheroid has one continuous radial slot. This divides the spheroidinto two or four portions. The spheroid 50 may have more slots thanshown.

As best seen in FIG. 5, the neck 28 has an internal bore 66 that extendsfrom a bottom surface 64 of the first end 48 through the interior of thesecond end (spheroid) 50. The bore 66 has a first portion 68 that isthreaded and a second portion 70 that is tapered. Particularly, thesecond portion 70 is tapered in the spheroid 50, i.e. from the end ofthe threaded portion 68 toward the top of the spheroid 50. The secondportion 70 is shaped such that the diameter reduces in a direction fromthe end of the first (threaded) portion 68 to the spherical end. Thebore 66 is preferably, but not necessarily, concentric with the outerdiameter of the first end 48.

The threaded portion 68 allows the threaded insertion and advancement ofthe locking screw 30. The tapered portion 70 in conjunction with thefirst radial slot and/or the second radial slot provides a radialspreading of the spheroid 50 (i.e. radial spreading of the portionsdefined by the radial slots) when the locking member 30 advances intothe tapered portion 70. The spherical outer diameter is enlarged due tothe expansion of the radial slots in the sphere 50 through advancementof the locking screw 30.

Referring to FIGS. 6 and 7, there is depicted the locking and/oradjustment member or screw 30. The locking screw 30 is characterized bya body 78 in the general shape of a tube, cylinder, pin, rod or thelike. The body 78 has a first section 80 of a generally circular outerdiameter with threads 82 on one end thereof. The threads 82 arecompatible with the threaded portion 68 of the bore 66 of the neck 28.The body 78 has a configured bore 84 in an end 83 thereof. The threadedbore 84 is shown configured for a hex wrench (not shown). The hex wrenchis used to thread the locking member 30 into the bore 66 of the neck 28.Of course, other configurations and/or manners of advancing the lockingmember 30 into the neck 28.

The body 78 also includes a second portion 86 on an end of the firstportion 80. The second portion 86 is tapered from a junction point to anend 87. The taper corresponds, but is larger in diameter, to the taperedportion 70 of the neck. Thus, as the second (taper) portion 86 extendsinto the tapered portion 70 of the bore 66, the spheroid 50 radiallyexpands. The expansion of the spheroid 50 fixes the head 26 in itsspatial orientation.

Referring to FIGS. 8-11 there is depicted the head 26. The head 26 ischaracterized by a body 90 formed as a general partial spheroid.Particularly, the body 90 is shaped to conform to a glenoid. The body 90has an articulation surface 92 conforming to the general partialspheroid and a bottom surface 94. It should be appreciated that the head26 represents any size shoulder prosthesis head. The subject inventionallows the use of various sized heads with the other components of thepresent shoulder prosthesis 20. While a head of only one size isultimately used for the shoulder prosthesis 20 when implanted into thepatient, the components of the present shoulder prosthesis 20 allowvarious sized heads to be trialed and/or used when the humeral component22 is implanted into the humerus (i.e. during and/or after the time atwhich the humeral component 22 is final stage implanted in the humerus).The various heads may be variously proportioned and/or sized.

The head 26 further includes a recess, cavity or the like 96 defined byan inner surface 97 within the body 90 that is open at opening 101 onthe underside 94. The inner surface (wall) 97 and thus the cavity 96 isgenerally spheroid shape in general conformance to the spheroid head 50of the neck 28 of the conjoining member 24. The cavity 96 is sized toreceive the spheroid 50. Particularly, the cavity 96 has a diameter thatis slightly greater than the diameter of the spheroid 50.

The opening 101 has a shape or configuration defining a profile. Thisprofile can be considered in a plane defined by the underside 94. Itshould be appreciated that the profile of the opening 101 in the planeof the underside 94 is the same as the profile of a plane taken alongthe center of the spheroid 50 from flat 52 to flat 54 (or other keystructure as the case may be). This allows the spheroid 50 to be keyedto the opening 101 in one rotational position.

In the present case, the profile 101 is spheroid with two flats 98 and100. The flats 98 and 100 extend into the cavity 96 generallyperpendicular to the undersurface 94. The flats 98 and 100 may extendfrom only approximately 2 mm or enough to provide an axial stop for thespheroid 50 against axial removal therefrom, once the spheroid 50(member 28) is received into the cavity 96 and rotated as describedherein, or may extend up to an equator of the spheroid 50. As such,other profiles or keys and thus spheroid configurations may be used.Such other configurations could include the use of dowel pins insertedfrom the sides of the head (with slots in the neck body). However, inthe preferred embodiment, the embodiment that provides the greatestsurface area of contact, thus 90° of contact at two ends, is best. Whilenot necessary, the flats 98 and 100 are illustrated as disposed 180° ordiametrically opposite one another.

It should be appreciated that the manner of releasable attachmentbetween the conjoining member 24 and the head 26 is contemplated to andthus may vary in configuration. As an example, the cavity or receptaclein the head 26 may be fashioned or configured as a stepped bore with orwithout a key structure. The second end 50 of the neck 28 would thus befashioned or configured as complementary to the stepped bore. In anotherexample, the cavity or receptacle in the head 26 may be configured as acone or conical shaped with or without a key structure. Again, thesecond end 50 of the neck 28 would thus be fashioned or configured ascomplementary to the cone. As yet another example, the cavity orreceptacle in the head 26 may be configured as an interrupted spherewith or without a key structure. Again, the second end 50 of the neck 28would thus be fashioned or configured as complementary to theinterrupted sphere. Various combinations that allow the head to bereleasably affixed or joined with the conjoining member are contemplatedand thus may be used.

The cavity 96 is configured to receive the full spheroid 50 once thespheroid 50 has been properly aligned and then inserted into the cavity96. With respect to this feature, which releasably locks the neck 28 tothe head 26, reference is made to FIGS. 12-14. FIG. 12 depicts the neckbody 46 being introduced into the cavity 96 of the head body 90.Particularly, the spheroid 50 is being inserted into the cavity 96.Because of the flats 98 and 100, the spheroid 50 must be aligned suchthat the flats 52 and 54 of the spheroid 50 align with the flats 98 and100 (either ones) of the opening 110. This allows the spheroid 50 to befully received in the cavity 96 (see FIG. 13). The spheroid 50 isaxially beyond the flats 98 and 100 when fully received in the cavity96.

Once the neck 28 conjoins the head 26 as depicted in FIG. 13, the neck26 is rotated as depicted by the arrow 110. Particularly, the neck 28 isrotated a quarter turn (90°) in either direction (the arrow, however,depicting only one direction, i.e. to the right). This aligns the flats98 and 100, and 52 and 54 at 90° relative one another (see FIG. 14wherein only the flats 98 and 100 of the opening 110 can be seen sincethe flats 52 and 54 are 90° therefrom). This prevents the axial removalof the neck 28 from the cavity 96 (without 900 rotation of the neck 28because the spheroid 50 cannot pass through the opening 110 because ofthe flats 98 and 100. At this point, the head is still able to rotateabout two orthographic axes relative to the spheroid 50.

In FIG. 14, the head (particularly the undersurface 94) defines a planerepresented by the arrow 104. The neck 28 also defines a planerepresented by the arrow 106. Particularly, a plane of the neck 28 isdefined by a plane perpendicular to a longitudinal axis of the neck 28taken along the bore 66 thereof. Offset of the head 26 relative to theneck 26 may be defined as an angle deviation relative to a 90° anglefrom the longitudinal axis of the neck 28 represented by the arrow 108.In FIG. 14, there is no offset, since the angle α is 90°.

FIG. 15 depicts an offset of the head 26 relative to the neck 28 sincethe angle α is greater than 90° (i.e. the neck body 46 is angled to theleft). FIG. 16 depicts an offset of the head 26 relative to the neck 28since the angle α is less that 90° (i.e. the neck body 46 is angled tothe right). The head 26 is infinitely adjustable along the twoorthographic axis to set the spatial orientation of the head 26 relativeto the neck 28 and thus the humeral component 22. This may beaccomplished either before or after the humeral component 22 is set inthe humerus of the patient.

It should be appreciated that FIGS. 14-16 only depict angularorientation relative to one axis of rotation. The other axis of rotationis orthographic to the one depicted and, while not shown, exhibits thesame angular displacement in the respective spatial orientations.

Once the appropriate angular orientation of the head 26 is determined,the locking member 30 is introduced into the neck bore 66. Referring toFIG. 17, an exemplary orientation of the head 26 relative to the neck 26is shown. The locking member or screw 30 characterized by body 78 isadvanced axially into the neck body 46 by action of the mating threads.As the tapered portion 86 of the locking screw 78 enters the taperedportion 70 of the neck bore 66, the spheroid 50 is spread to expand intothe cavity 96. Such radial expansion fixes the orientation of the headrelative to the neck 28.

As depicted in FIG. 18, the conjoining member 24 is releasably affixedto the humeral component 22 with the head 26 releasably affixed to theconjoining member 24. The conjoining member 24 and thus the head 26 maythus be removed from the humeral component 22 especially after thehumeral component 22 has already been permanently implanted into thehumerus of the patient. Particularly, adjustment to the head 26 is madein vivo, making the adjustment procedure easier for a surgeon, as alllandmarks for adjustment are present during the adjustment process.Further, the surgeon can cement or otherwise affix the humeral component22 in an optimal position for fixation, and adjust humeral head positionwithout interfering with this fixation. For example, different sizeheads may be tried and/or changed and spatially oriented while thehumeral component 22 is implanted in the humerus.

It should be appreciated that the conjoining member 24 is releasably orremovably situated on the humeral stem 22. At the same time orindependent therefrom, the head 26 may be fixed on the conjoining member24. This allows the head and locking component to be removed duringpreparation of the glenoid joint surface. This provides for a smoothersurgical technique, possibly lowering anesthesia times, as well asprovide other advantages. The subject configuration also allows retrofitof a new head (with a conjoining component) onto a previously implantedshoulder prosthesis in need of revision.

Referring now to FIG. 19, there is depicted an exemplary alternativeembodiment of a humeral head, generally designated 26′. The head 26′ maybe used in any situation where the head 26 described above may be used.The head 26′ also functions in the same manner as the head 26.Additionally, the humeral head 26′ may come in various sizes. Inaccordance with an aspect of the subject invention, the configuration ofthe humeral head 26′ allows an alignment system as described herein tobe used.

The head 26′ is defined by a body 90′ in like manner to the body 90 ofthe head 26. The body 90′ includes an articulation surface 92′ again inlike manner to the articulation surface 92 of the body 90. The body 90′has an interior spheroid cavity 96′ defined by a spheroid wall orsurface 97′. A bore 122 is defined in an apex of the articulationsurface 92′. The bore 122 provides communication between the cavity 96′and outside of the articulation surface 92′. The bore 122 further ispreferably, but not necessarily tapered. In the exemplary embodiment ofthe head 26′, the tapered bore 122 tapers from the spherical cavity 96′to the articulation surface 92′.

The body 90′ further includes an inner and annular groove 120. Theannular groove 120 extends an axial distance into the body 90′. Anopening 101′, providing communication with the cavity 96′, begins from aplane defined at an annular axial end of the annular groove 120. One 98′of two flats is shown, the other of which is disposed diametricallyopposite the flat 98′ and thus not seen in the view of FIG. 19, thatextend from the opening profile 101′ axially into the cavity 96′. Theflats function in the same manner as the flats 98 and 100 describedherein. The cavity 96′ is sized to receive an appropriate spheroid endof a neck of a conjoining component. Using this embodiment, a hex (orother configuration) on the locking screw can be on the tapered endthereof, thus allowing a hex (or other appropriate shaped) driver toactuate the locking screw through the head instead of from the undersideof the head.

The head 26′ also includes a first and second cutout of which only onecutout 124 can be seen in FIG. 19. The other cutout is disposeddiametrically opposite the cutout 124. The cutouts are utilized foralignment when used with a trialing jig as described below. It should beappreciated that the cutouts may instead be marks or markings on thehumeral head 26′ or other similar features.

Referring now to FIG. 20, there is depicted an exemplary embodiment of atrialing jig, jig or the like, generally designated 130 that may be usedwith the subject shoulder prosthesis 20. The jig 130 may also be used onshoulder prostheses other than those described herein. The jig 130 isconfigured to spatially position or orient a humeral head relative to aconjoining member or vice versa. It should be appreciated that the jig130 represents one particular embodiment the general principles of whichare described below along with alternative components.

Particularly, the trialing jig or jig 130 is used to spatially positionthe humeral head 26 on the neck 28 of the conjoining member 24 andtranslate the spatial positioning to a final implant construct (i.e. ahumeral head and a neck or e.g. conjoining component/member 24). Thismay be accomplished after the humeral component 22 has been implantedinto a resected humerus. The jig 130 consists of a retention body (body)having or retaining a rotatable, rotational, pivotable or pivotingmember that may or may not include an external lock or locking mechanismor member. One such jig is exemplified in FIG. 20.

Particularly, in FIG. 20, the body is embodied as a plate 131. The plate131 is here comprised of a first or lower plate 132 and a second orupper plate 134 although the plate 131 may be a single plate. The first(lower) and second (upper) plates 132 and 134 are joined such that innersurfaces thereof are joined and fixed. The first and second plates 132and 134 together define a cavity 138 therein., The cavity 138 is shownas a sphere or spheroid. However, it should be appreciated that thecavity 138 may be formed into another shape that allows a same shapedmember to rotate or pivot therein about or in at least two axes. Theseaxes can be orthographic or polar. For example, one can achieve the sameangular movement by rotating about an axis perpendicular to a plane ofthe plate (body) and any axis that lies within the plane of the plate.In a single body embodiment, the retention body would have a cavityformed therein. Particularly, the first plate 132 has a first sphereportion or spherical hole 140 cut out therefrom, while the second plate134 has a second sphere portion or spherical hole 142 cut out therefrom.The first and second sphere portions 140 and 142 together define thesphere or spheroid 138. Preferably, the first and second sphere portions140 and 142 are each half spheres or spheroids.

The first plate 132 also includes a tapered bore 144 that is incommunication with the first sphere portion 140 and thus the bottom ofthe sphere 138. Additionally, the body 131 may have a retention orlocking mechanism. In one form, and as shown in the Figures, theretention or locking mechanism includes a threaded bore 146 that extendsfrom an outside surface of the body (plate 131) to the sphere 138 (i.e.the surface defining the sphere 138). Particularly, as shown, thethreaded bore 146 extends from an outside surface of the first plate 132to the surface of the first sphere portion 140. The threaded bore 146 isadapted to receive a threaded set screw or the like. It should beappreciated that while the threaded bore 146 is shown in the first orlower plate 132, the threaded bore 146 may be disposed in the second orupper plate 134. Also, the orientation of the threaded screw bore 146may be varied appropriately.

Rather than a set screw as described above, a retention or lockingmechanism such as a spring-loaded cam mechanism actuated by a lever, maybe used as described herein. It should be appreciated that other typesof retention mechanisms may also be used.

The plate 131 has alignment marks or markings that are embodied asgrooves or etched lines 136. The grooves 136 are parallel to one anotherand provide alignment demarcations for the humeral head 26 with respectto the neck 28. The grooves 136 are disposed on an upper surface of thesecond plate 134 and run from one side thereof to another side thereof.These lines could also form a grid such as a Cartesian or polar grid.Furthermore, there could be a series of machined holes or detents. Thedevice could also provide incremental detents that fit with a protrusionin the head. In this manner, there could be precise replication of headrotation with an orientation angle transfer being accomplished inspecific increments.

Referring to FIG. 21, the jig 130 is depicted with various jigcomponents situated therein and/or thereon. It should be appreciatedthat the jig 130 is shown in FIG. 21 in sectional view taken along line21—21 of FIG. 20. However, a set screw or the like 148 is shown disposedin the threaded bore 146. Rotation of the set screw 148 in one directionadvances the set screw 148 toward the sphere 142, while rotation of theset screw 148 in an opposite direction withdraws the set screw 148. Alsoshown in FIG. 21 which is not depicted in FIG. 20 is a sphere 150. Thesphere 150 is disposed in the spherical hole or opening 142. The sphere150 is sized to closely fit the spherical hole 142 such that the sphere150 can freely rotate within the spherical hole 142 but which cannottranslate therein (i.e. relative to the plate 131). The sphere 150 isrotatable about at least two (2) axes that are perpendicular and extendthrough a center of the sphere 150. The sphere 150, however, cannottranslate within or with respect to the body 131.

The sphere 150 includes a bore 152 that is configured in like manner(but slightly larger) than the neck body 46 (of the shoulder prosthesis20) in order to receive a neck body 46 therein. Particularly, the bore152 is tapered to receive the tapered neck body 46. The bore 152 has anaxis running through the center of the sphere 150. The sphere 150 isable to rotate in various axes as represented by the arrows 154 and 156.The set screw 148 is able to lock rotation of the sphere 150 by contacttherewith, particularly via advancement of the set screw 148.

It should be appreciated that the “sphere” 150 may be any shape toconform to or with the shape of the cavity 138. Depending on the shapeof the rotating member and tolerances between the rotating member andthe cavity, a retention or locking mechanism may not be necessary. Therotating member may fit with enough tolerance to be rotated or pivoted,but not freely.

Referring now to FIG. 23, there is depicted another exemplary embodimentof a shoulder prosthesis, generally designated 200, in accordance withthe principles of the subject invention. The shoulder prosthesis 200includes a humeral component or stem 202, a conjoining member orstructure 204, and a humeral head 210.

The humeral component 202 (of which only a portion thereof is shown inFIG. 23) includes a body 212 having a head 214 and stem (not shown). Thehead 214 has a surface 216 in which is situated a concavity 218. Theconcavity 218 is configured in a manner to receive a component of theconjoining member 204. Preferably, the concavity 218 is a taperedconcavity and, more particularly is a Morse taper concavity.

The humeral head 210 is characterized by a body 228 having anarticulation surface 230 and an underside or undersurface 232. In FIG.23, the body 228 includes a concavity 234 of a particular configuration.It should be appreciated in like manner to the other embodimentsdescribed herein, that the concavity 234 may alternatively be aconvexity of a particular configuration. In FIG. 23, the concavity 234is configured as a sphere or spheroid. Other configurations may be usedfor the concavity or convexity of the head 210.

The conjoining member 204 includes a neck member 206 and a locking pin208. The neck member 206 is characterized by a body 220 having a taperedportion 222 and a convexity 224. The tapered portion 222 is configuredin a substantially complementary manner to the concavity 218 of thehumeral component 202 for releasable mating (releasable fixation)therewith in a manner as described above in conjunction with the otherembodiments. The convexity 224 is of a particular configuration toreleasably mate with the concavity 234 of the head 210. It should beappreciated in like manner to the other embodiments described herein,that the convexity 224 may alternatively be a concavity of a particularconfiguration. In FIG. 23, the convexity 224 is configured as a sphereor spheroid. The sphere 224 preferably includes slots in like manner tothe other shoulder prostheses described herein. Other configurations maybe used for the concavity or convexity of the neck 206. The neck 206also includes a tapered bore 226 extending therethrough for receivingthe pin 208. The convexity/concavity 224 of the conjoining neck 220 isadapted to releasably join or mate with the concavity/convexity 234 ofthe head 210.

The pin 208 is characterized by a body 236 having a cylindrical end 238and a tapered end 240. The pin 208 is oversized in length with respectto the neck 206, but is sized to be received in the bore 226 of the neck206. The tapered end 240 of the pin 208 spreads the spheroid 224 in likemanner to that shown and described above with respect to the otherembodiments.

In use, the head 210 is positioned appropriately on the neck 206. Thelock pin 208 is then situated into the bore 226 of the neck 206. Theconstruct (head 210 and conjoining member 204 is then situated on thehumeral component 202. When the end 242 of the pin 208 bottoms out(contacts) end 244 of the cavity 218, the pin 208 is advanced throughthe conjoining (neck) member 206. Impaction of the head 210 then seatsthe lock pin taper 240 in the mating taper of the convexity 224 therebysecuring the head 210 onto the conjoining member 206. In thisembodiment, threads are eliminated in both the pin and neck of theconjoining member 204.

Use of the Jig

It should be appreciated that the jig 130 is adapted for use with theshoulder prosthesis 20. Particularly, the jig 130 is adapted for usewith the conjoining member 24 and the head 26 as described herein.

Referring additionally to FIG. 22, an exemplary manner of use of the jig130 will be described. It should be appreciated that an implantconstruct is made of a humeral head and a neck. As described above, theimplant construct allows rotational movement between the head and theneck wherein the neck may be considered as movable relative to the heador the head may be movable relative to the neck. In either case, thepositioning or orientation of the two components (i.e. the head andneck) may is releasably lockable as provided herein. Further, there istypically a trial implant construct and a final implant construct.

A trial implant construct is presented to the jig 130 in a lockedposition, meaning that the neck 46 is locked relative to the head 26′.The trial implant construct is used to vary the position of the head 26after the humeral component 22 has been implanted in the humerus. Thetrail implant is thus used to obtain an appropriate spatial positioningof the head. This spatial positioning is then transferred to a finalimplant construct with the aid of the present jig 130. Particularly, asshown in FIG. 22, the neck 46 is inserted into the bore 152 of thesphere 150. The sphere 150 is free to rotate within the spherical hole142. Once the neck 46 is within the bore 152 of the sphere 150, thetrial implant construct is positioned through movement of the sphere 150such that the flat side (undersurface 94′) of the head 26′ is flush withthe upper surface 135 of the plate 131. Particularly, when the taperedneck 46 is positioned in the sphere 150 and the head 26′ is positionedwith its bottom surface 94′ flush with the upper surface 135, the sphere150 rotates appropriately. The head 26 is rotated until the alignmentmarks on the head 26 align with the alignment marks 136 on the jig 130.

Once the head is properly aligned on the jig 130, the set screw 148 isadvanced toward the sphere 150 to lock the sphere 150 from rotation. Thetrial implant construct is then removed from the jig 130. This leavesthe sphere 150 in a locked reference position for transferring thespatial positioning of the head (i.e. spatial positioning of the headand neck) to a final implant.

The final implant construct is then placed in the jig in a loose state.Particularly, the neck 46 of the final implant construct is placed inthe bore 152 of the locked sphere 150, with the head 26 positioned onthe neck 46, but not locked thereto. Once the flat side 94 of the head26 is flush against the upper surface 135 of the plate 131 and thealignment mark or marks on the head 26 are properly aligned with thealignment mark or marks of the plate 135, the head 26 may be fixed inspatial position relative to the neck 46 as described herein. The finalimplant construct may then be removed from the jig 130 and implantedonto the humeral component 22.

There is a plurality of advantages of the subject invention arising fromthe various features of the shoulder prosthesis head alignment jigdescribed herein. It will be noted that alternative embodiments of theshoulder prosthesis head alignment jig of the subject invention may notinclude all of the features described yet still benefit from at leastsome of the advantages of such features. Those of ordinary skill in theart may readily devise their own implementations of a shoulderprosthesis head alignment jig that incorporate one or more of thefeatures of the subject invention and fall within the sprit and scope ofthe subject invention.

What is claimed is:
 1. A jig for transferring spatial positioning of ahumeral head of a first construct relative to a conjoining member of thefirst construct to a second construct having a humeral head andconjoining member, the jig comprising: a body defining a flat surface; acavity within said body; a pivoting member disposed within said cavity,said pivoting member having a configured bore accessible through saidbody and adapted to freely pivot within said cavity; and locking meanssituated in said body and adapted to selectively engage said pivotingmember to releasably fix a rotational position of said pivoting member;wherein said configured bore is adapted to receive a conjoining memberof the first construct and orient said conjoining member relative to aposition of the head on said flat surface of said body via pivoting ofsaid pivoting member, said locking means releasably fixing rotationalposition of said pivoting member during which the first construct isremoved and a conjoining member of a second construct is placed thereinfor alignment according to the fixed rotational position of saidpivoting member as a head of the second construct is placed on theposition of the head of the first construct on said body, the conjoiningmember then affixed to the head of the second construct.
 2. The jig ofclaim 1, wherein said body comprises a plate.
 3. The jig of claim 2,wherein said plate comprises a first plate having a first portion and asecond plate having a second portion, the first and second portionsdefining said cavity.
 4. The jig of claim 1, wherein said body furtherincludes a plurality of alignment markings on a surface of said body. 5.The jig of claim 4, wherein said plurality of alignment markingscomprises grooves on an upper surface of said body.
 6. The jig of claim1, wherein said locking means comprises a set screw.
 7. The jig of claim6, wherein said set screw is threaded and said body further includes athreaded set screw bore extending from an outside surface of said bodyto said cavity.
 8. A jig for transferring spatial orientation of ahumeral head to a conjoining member of a first construct to a humeralhead and conjoining member of a second construct, the jig comprising: abody having an upper surface, a spherical cavity, and an opening in saidupper surface; a sphere disposed in said spherical cavity and having abore configured to receive a neck of a first construct, said sphereadapted to freely rotate within said spherical cavity and withouttranslation relative to said body; and locking means situated in saidbody and adapted to selectively engage said sphere to releasably fix arotational position of said sphere; wherein said configured bore isadapted to receive a neck of the first construct and orient said neckrelative to a position of the head on said flat surface of said body viarotation of said sphere, said locking means releasably fixing rotationalposition of said sphere during which the first construct is removed anda neck of a second construct is placed therein for alignment accordingto the fixed rotational position of said sphere as a head of the secondconstruct is placed on the position of the head of the first constructon said body, the neck then affixed to the head of the second implantconstruct.
 9. The jig of claim 8, wherein said body comprises a plate.10. The jig of claim 9, wherein said plate comprises a first platehaving a first spherical portion and a second plate having a secondspherical portion, the first and second spherical portions defining saidspherical cavity.
 11. The jig of claim 8, wherein said body furtherincludes a plurality of alignment markings on an outside surfacethereof.
 12. The jig of claim 11, wherein said plurality of alignmentmarkings comprises grooves.
 13. The jig of claim 8, wherein said lockingmeans comprises a set screw.
 14. The jig of claim 13, wherein said setscrew is threaded and said body further includes a threaded set screwbore extending from an outside surface of said body to said sphericalcavity.
 15. A method of transferring spatial orientation of a firstconstruct having a humeral head adapted to be releasably affixed to aconjoining member to a second construct having a humeral head adapted tobe releasably affixed to a conjoining member, the method comprising thesteps of: fixing a spatial orientation of a humeral head relative to aconjoining member of a first construct; placing the conjoining member ofthe first construct into a jig, the jig comprising: a body defining aflat surface; a cavity within said body; a pivoting member disposedwithin said cavity, said pivoting member having a configured bore andadapted to freely rotate within said cavity; and locking means situatedin said body and adapted to selectively engage said pivoting member toreleasably fix a rotational position of said pivoting member; whereinsaid configured bore is adapted to receive a conjoining member of thefirst construct and orient said conjoining member relative to a positionof the head on said flat surface of said body via rotation of saidpivoting member; fixing the rotational position of said pivoting memberthe locking means; removing the first construct; and placing aconjoining member of a second construct in the jig for alignmentaccording to the fixed rotational position of said pivoting member as ahead of the second construct is placed on the position of the head ofthe first construct on said body, the conjoining member then affixed tothe head of the second construct.